 <!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			.one{border: ;}
		</style>
	</head>
	<body>
		<div class="one">第一个盒子</div>
		<div class="one">第二个盒子</div>
		<div class="two">第三个盒子</div>
		<div class="two">第四个盒子</div>
		<script>
			var Odiv1 = document.getElementsByClassName("one");
			var Odiv2 = document.getElementsByClassName("two");
			Odiv1[0].style.fontWeight = 'bold';
			Odiv2[0].style.background = 'red';
			Odiv1[1].style.color = 'orange';
			Odiv2[1].style.border = '1 solid black';
			var divall = document.querySelector(".two");
			console.log(divall);
		</script>
	</body>
</html>